package com.zijin.utils;

import lombok.extern.slf4j.Slf4j;

/**
 * @Title: aa
 * @Author JWei Xu
 * @Package com.zijin.utils
 * @Date 2024/12/7 12:09
 * @description:
 */

@Slf4j
public class SnowflakeIdGeneratorUtil {

    // 自定义纪元（2002-11-20 00:00:00 UTC）
    private final long twepoch = 1037721600000L;

    // 每一部分占用的位数
    private final long workerIdBits = 5L;
    private final long datacenterIdBits = 5L;
    private final long sequenceBits = 12L;

    // 每一部分的最大值
    private final long maxWorkerId = -1L ^ (-1L << workerIdBits);
    private final long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);

    // 每一部分向左移的位数
    private final long workerIdShift = sequenceBits;
    private final long datacenterIdShift = sequenceBits + workerIdBits;
    private final long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;

    private long sequenceMask = -1L ^ (-1L << sequenceBits);

    // 数据中心ID和工作机器ID
    private long workerId;
    private long datacenterId;
    private long sequence = 0L;
    private long lastTimestamp = -1L;


    public SnowflakeIdGeneratorUtil(long workerId, long datacenterId) {
        log.info("wo:{},id{}",workerId,datacenterId);
        if (workerId > maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("工作机Id不能大于 %d 或小于 0", maxWorkerId));
        }
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
            throw new IllegalArgumentException(String.format("数据中心 Id 不能大于 %d 或小于 0", maxDatacenterId));
        }
        this.workerId = workerId;
        this.datacenterId = datacenterId;
    }

    public synchronized long nextId() {
        long timestamp = timeGen();

        if (timestamp < lastTimestamp) {
            throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
        }

        if (lastTimestamp == timestamp) {
            sequence = (sequence + 1) & sequenceMask;
            if (sequence == 0) {
                timestamp = tilNextMillis(lastTimestamp);
            }
        } else {
            sequence = 0L;
        }

        lastTimestamp = timestamp;

        return ((timestamp - twepoch) << timestampLeftShift) |
                (datacenterId << datacenterIdShift) |
                (workerId << workerIdShift) |
                sequence;
    }

    protected long tilNextMillis(long lastTimestamp) {
        long timestamp = timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = timeGen();
        }
        return timestamp;
    }

    protected long timeGen() {
        return System.currentTimeMillis();
    }

}
